The present invention relates to a transformer, specifically a transformer having a gap between a primary coil and a secondary coil.
As shown in FIG. 24, as a transformer having a gap between a primary coil 10 and a secondary coil 20, a following configuration is known: an E-type core 30e (an iron core or a magnetic core) having an E-shaped cross section is wound with, for example, the secondary coil 20, and the E-type core 30e with the secondary coil 20 being wound therearound is arranged to face the primary coil 10. In this connection, however, following problems exist: it is difficult to manufacture the integrally-formed E-type core 30e; and even if such manufacturing can be achieved, manufacturing costs thereof are costly.
In order to solve the above problems, it has been suggested to form an E-type core by stacking plate-like cores on one another, thereby facilitating the manufacturing of the E-type core and reducing the manufacturing costs (see, for example, Unexamined Japanese Patent Application Publication No. 2008-120239; hereinafter, referred to as “Patent Document 1”).
Patent Document 1 also suggests, as an embodiment of an E-type core capable of handling a small amount of an electric power compared with the integrally-formed E-type core, a transformer having a configuration in which parts of the core are removed in a striped manner. This configuration can provide an advantage of reducing materials to be used for the core, thereby reducing a weight of the transformer.
Moreover, since there is a problem in which the E-type core is heavy, it is suggested to use a flat-plate like core for the purpose of reducing a weight of a transformer (see, for example, Unexamined Japanese Patent Application Publication No. 2008-087733; hereinafter, referred to as “Patent Document 2”). As shown in FIG. 25, the flat-plate like core 30p is arranged adjacent to a secondary coil 20 such that the secondary coil 20 is located between the flat-plate like core 30p and a primary coil 10. Alternatively, the flat-plate like core 30p is arranged adjacent to the primary coil 10 such that the primary coil 10 is located between the flat-plate like core 30p and the secondary coil 20 (this arrangement is not shown).